This invention relates to medical grafting methods and apparatus, and more particularly to methods and apparatus for installing tubular bypass grafts primarily with intraluminal methods with the assistance of surgical and minimally invasive methods and apparatus.
A conventional bypass grafting technique is illustrated at FIG. 1, which shows a patient's aorta 10 with a coronary artery 12 branching off the aorta. A narrowing 14 in coronary artery 12 is restricting blood flow from aorta 10 to downstream portions of the coronary artery, thereby preventing the patient's heart from receiving all the blood it needs for normal operation. In more serious conditions, the coronary artery may be entirely occluded. To remedy this condition, a bypass graft around narrowing 14 is needed, and one way to provide such a bypass is to add a graft conduit 15 from aorta 10 (e.g., at location 16) to a downstream portion of coronary artery 12 (e.g., at location 18). Sutures 20 are typically applied to “proximal” anastomosis location 16, i.e., at the joining of a graft conduit 15 with the side wall of the aorta 10 and “distal” anastomosis site 18, i.e., at the joining of the graft conduit 15 with the side wall of the coronary artery 12. Failure of the bypass circuit often occurs at the anastomosis sites due to injury or to poor fluid dynamics. Such tissue stress may trigger a healing response that ultimately reduces the patency of the graft.
Conventional suturing techniques may contribute to the failure of the distal anastomosis. The sutures 20 themselves may initiate injury to the graft vessel at coronary anastomosis site, which is already in high stress. When veins, such as the saphenous vein, are used for graft material, the high arterial pressure may dilate the vein to a larger diameter than it would experience under typical venous pressure. At the anastomosis site, the combination of the sutures and the arterial pressure amplifies the stress on the tissue, resulting in tissue injury and reduced patency.
Typical conventional techniques nevertheless require that the patient's heart be stopped and the patient be placed on cardiopulmonary bypass (CPB) to oxygenate and circulate the blood during the procedure. Stopping of the heart and CPB is typically required to allow effective suturing of the anastomosis. Suturing also requires blood flow to be stopped for optimal anastomosis. As a result, the patient is placed on CPB to provide a bloodless field and a still heart for the surgeon to attach the graft vessels. However, it is known that CPB can be very time consuming, costly and dangerous to the patient. Complications may include emboli, blood degradation, and damage to tissue from the use of cannulas. Alternatives to CPB may include the cross-clamping of arteries, which may damage the vessels or dislodge deposits such as atherosclerotic plaque from the lining of the vessel walls.
Goldsteen et al. U.S. Pat. No. 5,976,178 shows, among other things, methods and apparatus for installing tubular bypass grafts intraluminally. (The Goldsteen et al. reference is hereby incorporated by reference herein in its entirety.) The Goldsteen et al. reference shows methods and apparatus in which each end of the graft site is approached separately and intraluminally, penetrated, and then a longitudinal structure (e.g., element 150 in the Goldsteen et al. reference) is established between the ends of the graft site. This longitudinal structure may extend intraluminally all the way out of the patient's body from both ends of the graft site. The graft is fed into the patient's body intraluminally along the longitudinal structure until it is in the desired position extending from one end of the graft site to the other. Each end of the graft is then secured by anastomosis at the respective end of the graft site and the longitudinal structure is withdrawn from the patient.
In some cases, it may not be necessary or desirable to separately approach both ends of the graft site. Sullivan et al. U.S. patent application Ser. No. 08/844,992, filed Apr. 23, 1997, shows, among other things, methods and apparatus for allowing a longitudinal structure to be extended intraluminally to one end of a graft site. (The Sullivan et al. reference is hereby incorporated by reference herein in its entirety.) At that end of the graft site the longitudinal structure passes out of the body structure lumen and extends extraluminally to the other end of the graft site. At the other end of the graft site, the longitudinal structure re-enters the body structure lumen. The graft is introduced intraluminally along the longitudinal structure until it passes out of the body structure lumen at the first end of the graft site and extends to the second end of the graft site. Both ends of the graft are then secured by anastomosis at the respective opposite ends of the graft site, and the longitudinal structure is axially withdrawn from the patient.
Under some circumstances, it is preferable to dissect and relocate a vessel, such as an arterial blood source, in order to shift the vessel to the graft site. Sullivan et al. U.S. patent application Ser. No. 08/869,808, filed Jun. 5, 1997 shows methods and apparatus for shifting a vessel and performing an anastomosis intraluminally.
What is needed are methods and apparatus that provide the limited trauma of intraluminal methods but which also provide greater access or visibility during certain steps in the bypass procedure.
It is therefore an object of this invention to provide improved methods and apparatus for intraluminal installation of alternative tubular connections, such as bypass grafts and connections.
It is a more particular object of this invention to provide methods and apparatus for intraluminally installing bypass grafts which use simplified intraluminal apparatus to make the graft connection with surgical assistance or surgical access.
It is another object of the invention to reduce the patient trauma and risk of emboli, cannulation, and cross-clamping.
It is another object of the invention to reduce the procedural time and cost for current procedures.